1. Field of the Invention
This invention relates to wind powered or sail assisted watercraft and more particularly those watercraft using a single submerged hydrofoil for stabilization and improved performance.
2. Description of Prior Art
A number of patents have been granted covering hydrofoil devices intended to counteract the heeling moment imparted by wind pressure on the sails and masts of small sailing craft or saiboats. For monohull saiboats, this heeling moment causes the boat to heel or roll around the longitudinal axis of the hull. Those monohull sailboats with a deep and heavy ballast keel typically will heel until deck edge immersion occurs, at with time drag increases dramatically and performance erodes. In some cases, the sailboat may swamp or downflood. (Capsizing is rare, except in heavy seas, as the heeling moment exerted by wind on sails and masts is reduced as the angle of heel increases and wind spills off of sails.) Those monohull sailboats without a deep and heavy ballast keel typically will swamp or capsize. For multihull sailboats, this heeling moment causes the windward hull to rise up relative to the leeward hull and will eventually result in the boat capsizing or “turning turtle.”
Patented devices intended to counteract heeling moment using hydrofoil technology are typically complicated mechanical devices involving many moving parts. Most involve two or more foils. Most employ complex sensing and feedback components intended to alter the angle of attack of, and therefore the lift generated by, the foil or foils, depending on the speed of the boat and/or the heeling moment imparted by sail and mast.
None of these existing devices has been successfully applied to address the problem of stabilizing small, lightweight paddling kayaks or canoes such that they can be operated both as high performance, human-powered watercraft and as high performance, wind-powered watercraft. This is because they lack the simplicity of design and construction, the lightness in weight, and the ease of assembly and disassembly required to make them practical and appealing to the owner of the sort of canoe, kayak, or small sailboat that can be transported on the top of a car or other vehicle.
The demand for such a device, and the lack of applicability of existing patented devices, is apparent from the many advertisements contained in magazine for kayakers. These advertisements show a variety of very small sails and twin outrigger floats, both rigid and inflatable, intended to provide the average paddler with an option for a simple, lightweight accessory package allowing wind assistance when a kayak is navigated downwind or with the wind near or abaft the beam. These advertisements clearly show that there is a market or demand for the sort of innovative device that is the subject of this patent application.
A review of existing patents suggests that none incorporates and combines the unique features of the device covered by this patent application: simplicity (single moving part), manual operation, rigidity (truss structure yielded by combining the control spar and the support spar), ease of assembly and disassembly, light weight and ease of transport, and low cost to manufacture.
The Hydrofoil Means for Stabilizing Watercraft in U.S. Pat. No. 3,286,673 to Nason, Nov. 22, 1966, involved three separate hydrofoils mounted on the main hull and to port and starboard of two auxiliary hulls, and dozens of complex moving parts. This device would not be adaptable for use with a small, “car-toppable” canoe, kayak, or sailboat.
The High Speed Sailboat in U.S. Pat. No. 3,747,549 to Shutt, Jul. 24, 1973, uses two horizontal hydrofoils and a “planing surface” that controls automatically the angle of attack of the smaller of the two horizontal foils. The entire device is mounted on an outrigger arm on the windward side of a monohull sailboat and contains dozens of moving parts with multiple levers and pivot points. Moreover, the anti-heeling feature of the foils is augmented by the weight of the operator, who sits on a hiking board and uses his weight to counteract heeling moment. Finally, the forces generated by the foils are not transmitted to hull via a simple truss structure, but rather through a cable that is attached to the top of the mast. The overall result is a complex system of parts unsuitable for weight, complexity, and cost to the problem of stabilizing a car-toppable canoe, kayak, or small sailboat.
The Hydrofoil Sailboat with Control Tiller in U.S. Pat. No. 4,228,750 to Smith, Oct. 21, 1980, is also extremely complex and ill-suited to the problem of stabilizing a car-toppable canoe, kayak, or sailboat. It uses two buoyant hydrofoils connected to, and controlled from, a monohull sailboat through “pairs of spreaders and multiple cables.” A sail mounted not on the hull but above the foils is supported by “a plurality of interconnected, prestressed spars” and is controlled and inclined by means of a hand crank.
The Sailboat with Hydrofoil Members in U.S. Pat. No. 5,636,585 to Schultz, Jun. 10, 1997, involves two outriggers to either side of a monohull sailboat and requires that water ballast be pumped into pontoons incorporated into the hydrofoils. The device thus involves many moving parts, cables, spars, pumps, and hoses. It is not suitable for stabilizing a car-toppable canoe, kayak, or small sailboat.
The Catamaran Stabilization Structure in U.S. Pat. No. 4,561,371 to Kelley, Dec. 31, 1985, involves three separate foils mounted on a catamaran with hulls of equal size. It is not suitable for stabilizing car-toppable canoe, kayak, or small sailboat.
The Twin Hull Boat with Hydrofoils in U.S. Pat. No. 5,520,137 to Arii, May 28, 1996, involves the use of multiple foils on a power driven catamaran. It has no applicability to the problem of stabilizing a car-toppable canoe, kayak, or small sailboat.